API-v2: Rename hoedown_callbacks to hoedown_renderer
API-v2: Let hoedown_renderer have a void* opaque...

...instead of passing it as a separate parameter.
API-v2: Simplify HTML API

 - html_renderopts is now private
 - hoedown_html_renderer() allocates options and renderer
 - so does hoedown_html_toc_renderer()
API-v2: Finish HTML API
Let the examples use the new API! :tada:
Let's keep hoedown.def updated
Solve conflicts from master

Conflicts:
	src/html.h
	src/html.c
Merge pull request #26 from jmendeth/prototype-api-v2

[prototype] API v2